[PATCH] nvme-pci: use NOWAIT flag for nvme_set_host_mem

[Sagi Grimberg]

Hey Keith,

> Thanks for the fix. It looks like we still have a problem, though.
> Commands submitted with the "shutdown_lock" held need to be able to make
> forward progress without relying on a completion, but this one could
> block indefinitely.

Can you explain to me why is the shutdown_lock needed to synchronize
nvme_dev_disable? More concretely, how is nvme_dev_disable different
from other places where we rely on the ctrl state to serialize stuff?

The only reason I see would be to protect against completion-after-abort
scenario but I think the block layer should protect against it (checks
if the request timeout timer fired).